Dynamic characteristics of heat transfer coefficient in pressurized bubble columns with viscous liquid medium

Abstract

Dynamic characteristics of heat transfer coefficient have been investigated in a pressurized bubble column (0.152 m, i.d. and 2.0 m in height) by adopting the chaos theory. Effects of gas velocity (0-0.12 m/s), pressure (0.1-0.6 MPa) and liquid viscosity (1.0-38.0 mPa s) on the immersed heater-to-column heat transfer characteristics have been examined. The temperature difference fluctuations between the immersed heater and the column content proper have been analyzed by means of attractor trajectories and correlation dimension to characterize the dynamic heat transfer behavior. The immersed heater-to-column heat transfer coefficient has increased with increasing gas velocity or pressure, but it has decreased with increasing liquid viscosity. It has been found that the attractor trajectories and correlation dimension are effective tools to describe the dynamic heat transfer behavior in the pressurized bubble columns with viscous liquid medium. The correlation dimension of the temperature fluctuations and the range of heat-transfer coefficient fluctuations have decreased with increasing pressure, but they have increased with increasing gas velocity or liquid viscosity. The heat transfer coefficient, correlation dimension of temperature difference fluctuations or the range of fluctuations of heat transfer coefficient, have been well correlated with operating variables. (C) 2002 Elsevier Science B.V. All rights reserved.